It is known in the art to line canals and ditches with concrete, using a front bulkhead and a rear troweling skirt which is moved longitudinally along the excavation as the machine progresses and as concrete is poured between the bulkhead and the skirt. Concrete is supplied by a traversing conveyor which moves across the machine from a supply. The concrete pours down through a plurality of treemie tubes upon the graded surface. A single cross conveyor or a skip car can also be used to transfer concrete from the supply to the opposite sides of the slip form. Various forms of concrete consolidating structures are disclosed in the art including a forward bulkhead which is mounted on an eccentric to provide oscillation and thus compaction of the concrete to the desired degree. These tools are suspended from a frame that extends across the canal and is supported by endless tracks at each end that run along the top of the canal banks.
These machines provide limited adjustment for various sizes of canals or ditches and include adjusting means that operate vertically to vary the depth of the slab. Some systems employ a continuously moving screed or traveling pan to smooth the concrete to the desired surface configuration which tools are carried on an endless chain between a pair of transversely spaced sprockets. Those machines which provide vertical adjustment of the screed and trowel depend on complicated linkages, usually of the parallelogram and articulated frame configurations to provide this function. Machines of this nature are custom made for canal and ditch work where large spans are required and there is little or no variation in the contour of the graded ditch.